Please describe how many large heae sink with formula 1x1 or 2x2 or .....

 

With a 30v input and the output shorted with 5A current, power dissipation in the regulator will be 150 Watts.

With the LM138 TO-3 case (K suffix package) your thermal resistance will be 1°C per Watt of power dissipation.

The maximum temperature limit for the TO-3 package is 150°C.

So, if you had the regulator frozen into a block of ice that would stay frozen under all conditions, thus maintaining the regulator's case (package) at 0°C, the regulator power dissipation would be at it's maximum limit when dissipating 150 Watts.

If you used the T suffix LM338 (TO-220 package) the thermal resistance is 4°C per Watt, and the maximum temperature is 125°C. This means that if you could maintain the package at 0°C, the dissipation limit would be 31.25 Watts, or at 30v input with the output shorted, slightly over 1A.

 

Thanks a lot SgtWookie
Very Very
Thanks a lot SgtWookie
Very Very
Thanks a lot SgtWookie
Very Very
Thanks a lot SgtWookie

 

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1. in this cct the output 1.3-30V if i want 0-30V output, than change in cct



2. i am using voltage regulator after current regulator that show in final Block diagram this is ok or not if any other method please explain it